This invention relates to wirings in semiconductor integrated circuits and more particularly to wirings of extremely low resistance using superconductive materials.
Further, this invention relates to a structure of wiring using an oxide superconductor material in the shape of a thin film, and more particularly to a structure of wiring adapted for multi-layer or multi-level wiring in a semiconductor device and for a multi-layer wiring substrate.
Further, this invention relates to an integrated circuit device provided with a thermo-detector or temperature sensor, and more particularly to an integrated circuit device integrating superconducting materials and adapted for detecting a change in temperature at a high sensitivity.
Further, this invention relates to a method of fabricating a superconductor thin film, and more particularly to a method of forming a pattern of a high-temperature superconductor thin film, adapted for forming a fine pattern.
In conventional devices using superconductive materials, as recited in JP-A-60-65582, harmful metals such as alkali earth metals like Ba or alkaline metals, or metals which form a deep level in silicon, are exposed.
Conventionally, normal conductors are used for packaging wirings. The resistance of the packaging wirings produces a delay and prevents increase in the operation speed of the integrated circuit device.
Use of a superconductor as the material for packaging wirings was proposed for solving the delay due to the resistance, in "Superconduction and its Applications" (published May 1986, Sangyo Tosho, Tokyo) pages 161-162. This article, however, does not refer to any concrete technological concepts.
In conventional semiconductor devices, the resistivity of conductive materials used for construction a have low dependence on temperature. The resistance does not change much even when the device is refrigerated to a low temperature. Therefore, the device performances also do not increase much. Refrigeration of a semiconductor device does not always provide a technically high effect.
For forming high temperature superconductor thin films made of sintered material on a substrate, evaporation, sputtering and application and sintering of organic solvent mixed with an organometal compound have been proposed, as recited in Japanese newspaper "Nikkan Kogyo" dated Apr. 24, 1987. Further, for shaping the high temperature superconductor thin film, ion-sputtering etching and wet etching using aqua regia are used.